Desiccant cartridge and method of making



Jan. 2, 1951 R. s. GAUGLER 2,536,274

DESICCANT CARTRIDGE AND METHOD 0F MAKING Filed Jan. 22, 1947 INVENToR.

i I BY ,Mk

Patented Jan. 2, 1951 DESICCANT CARTRIDGE AND METHOD OF MAKING RichardS. Gaugler, Daytonkphio, assignor to General Motors Corporation, Dayton,Ohio, a

corporation of Delaware Application January 2z, 1941, semi No. 723,591

4 Claims.

This invention relates to refrigerating apparatus and more particularlyto an improved drier unit for use in refrigerant circuits and to animproved method of making the drier unit.

It is an object of this invention to provide a low cost drier unit ordesiccant cartridge which is not subject to breakage when handledroughly.

It is another object of this invention to provide an improved method andapparatus for manufacturing drier units of uniform size.

It is another object of this invention to provide drier units of uniformsize in which granular particles of a desiccant material are compactlyarranged within an outer perforated casing.

VFurther objects and advantages of the present invention will beapparent from the following description, reference being had to theaccompanying drawings, wherein a preferred form of the present inventionis clearly shown.

In the drawing:

Figure l is an elevational view showing a woven wire tube of the typeused inthe manufacture of the drier unit;

Figure 2 is an elevational view with parts broken away showing apparatusused in the manufacture of the drier unit and showing one drier unit inthe process of manufacture;

Figure 3 is an elevational view of a ldrier unit; and,

Figure 4 is a sectional view taken on line 4-4 of Figure 3 showing thearrangement of the spiral reinforcing wire within the woven wire tubingwhich forms the outer casing of the unit.

This application is related to application S. N. 697,980, filedSeptember 19, 1946, wherein there is shown and claimed one form of drierunit.

It has been found desirable to maintain complete uniformity in the outerdimensions of the drier umts and to make them sufficiently rigid so thatthe likelihood of breakage during rough handling will be largely orentirely eliminated. Both of these desirable objectives are accomplishedby my invention as set forth more fully hereinafter.

The outer casing of the drier unit is made by taking a section ofexpansible woven wire tubing Il, such as shown in Figure 1 of thedrawing, and twisting the lower end of the tubing as indicated at I2 inFigures 2 and 3 and then inserting this into a sizing tube or fixture I4having an internal diameter substantially equal to the desired externaldiameter of the finished drier unit. As shown in the drawing, the tubingIl) consists of interwoven wires extending helically in oppositedirections.

(Cl. 21o-131) In order to expand the woven wire tubing to the desireddiameter, pressure is first applied to push the upper end toward thelower end of the tubing and then a helically wound relatively stiil'wire I6 is forced into the upper end of the tubing while the tubing ismounted within the fixture I4. Woven wire tubing of this type may bepurchased cheaplyvand comes in long lengths of small divthe funnel 20.

The fixture I4 is vibrated by means of the vibration producing element22 while the loose granular material is being fed into the tubing I0 soas to cause the granules to be packed in place. Since vibrationproducing elements are old and well known, and since the details ofconstruction of the vibrating element are immaterial they need not beshown or described in greater detail.

After the tubing I0 has been filled to the desired level, the upper endof the tubing'is twisted as indicated at 24 in Figure 3 so as to closethe upper end of the tubing. Closing the tubing against the ends of thewire I6 and the desiccant I8 prevents foreshortening of the tubingthereafter. Any dust which may result from abrasion of the particlesduring the filling operation may be blown off, if desired, during orsubsequent to the filling operation. The aembly is thereafter removedfrom the fixture I4 andis coated with a moisture permeable, moistureinsoluble but dustproof material.

Preferably granular4 anhydrous calcium sulphate is used as thedesiccant, although other materials such as lime, silica gel, or otheralkaliv earth oxides may also be used. The coating ma- V terial which Iprefer to use is cellulose acetate,

' although other materials such as ethyl cellulose, methyl cellulose, orany oi. the hydroscopic coatings of cellulose esters or ethers, may beused depending upon the particular application. Thus in a refrigeratingsystem employing Freon refrigerant, it is preferred to use anhydrouscalcium sulphate granules coated withvcellulose acetate so as tocompletely enclose the anhydrous calcium sulphate whereby fine particlesof calcium sulphate are prevented from passing through the coating. l

The coating operation may be performed by sat urating the entireassembly comprising the screen tubing Il, the reinforcing helical wireIB and a granular desiccant material Iii,v with a ve to ten percentsolution of celluloseacetate and thereafter allowing the excess solutionto drain oi from the assembly so as to leave a porous structure.Theassembly may be saturated in any manner such as by dipping it into aliquid solution of a coating material or by placing the assembly in avessel, evacuating the vessel of air. replacing the evacuated air withthe liquid solution so as to fill all of the voids, and thereafterremoving the assembly from the vessel and allowing the excess solutionto drain off leaving only a. thin cohesive binding coating on the parts.Woven wire tubing material which will provide approximately a 16-meshscreen closure for the desiccant material is preferably used.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. A cohesive drier unit of large effective surface area comprising aperforated casing; a hellcal-shaped reinforcng member within saidperforated casing contacting and supporting the inner wall of saidcasing to prevent its collapsing and crushing; a granular desccantmaterial within ,said casing; and a binding coating for said granulardesiccant material, said reinforcing member, and said casing comprisinga moisture permeable, moisture insoluble but dustproof combined bindingand coating material; said coating serving to bond said granulardesiccant, said re'nforcing member and said casing into a unitarycohesive structure.

2. The method of fabricating a drier unit of the type in which adesiccant material is disposed within an expansible woven wire tubewhich comprises closing one end of said tube, expanding said tube whileconfined within a fixture having an internal diameter substantiallycorresponding to the nal external diameter of said drier unit, placingan expander element within said tube for establishing the internaldiameter of said tube, placing granular desiccant material within thetube, closing the other end of said tube and thereafter applying amoisture permeable, moisture insoluble but dustprooi' binding coating tothe exposed surfaces of said desiccant material and said tube.

3. In combination, a flexible woven wire tube element having helicallyextending interlaced l 4 wires, a rigid helical wire within said tubelimiting inward exing of said tube element, said tube element havingclosed end-portions engaging the ends of said spiral wire so as toprevent foreshortening of said tube element, desiccant material withinsaid tube element, and a coating of water permeable bonding material onthe surface of said desiccant material and said helical wire and saidwoven wire tube element for increasing the rigidity of the assembb'.

4. The method of fabricating a drier unit of the type in which adesiccant material is disposed within an expansible woven wire tubewhich comprises closing one end of the tube, expanding the tube to thedesired nal diameter of the drier unit, placing an expander elementwithin said tube for establishing the minimum internal diameter of thetube, vibrating the tube and expander element while placing granulardesiccant material within the tube, closing the other end of-the tube,and thereafter applying a thin moisture permeable moisture insolubledustproof binding coating to the entire assembly including the entiresurfaces of the desiccant material andthe expander element and said tubeto bind the as- The following references are of record in the le of thispatent:

UNITED STATES PATENTS Number Name Date 913,325 Touzimsky Feb. 23, 19091,137,480 Gwynn Apr.- 27, 1915 1,218,975 yBrison Mar. 13, 1917 1,704,634Snider Mar. 5, 1929 1,839,350 Slagel Jan. 5, 1932 2,175,775 Hum Oct. 10,1939 2,203,815 Dahl et al June 11, 1940 2,260,608 Cormack Oct. 28, 19412,267,918 Hildabolt Dec. 30, 1941 2,365,149 Anderson Dec. 19, 19442,388,390 Cook et al. Nov. 6, 1945 2,433,531 Ryan Dec. 30, 1947 FOREIGNPATENTS Number Country Date 100,667 Australia Apr. 15, 1937 OTHERREFERENCES Mercks Index. 4th edition, 1930, Merck 8; Co. Inc., Rahway,N. J., p. 155.

